Method and apparatus for receiving data in human body communication system

ABSTRACT

The present invention provides a method and apparatus for receiving data in a human body communication system. The receiving apparatus, which comprises plural receiving electrodes, selects the optimum pair of receiving electrodes when receiving data, so that it can improve quality of received information and obtain position information of a sensor in the human body.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a 35 U.S.C. § 371 national phase conversionof PCT/KR2003/002938 filed 31 Dec. 2003, which claims priority of KoreanPatent Application No. 10-2003-0005058 filed 25 Jan. 2003.

TECHNICAL FIELD

The present invention relates to a method and apparatus for receivingdata in a human body communication system that can improve the qualityof received information and grasp the position information of a sensorin the human body by using plural receiving electrodes.

BACKGROUND ART

Various sensors for collecting medical information in the human bodyhave been developed and used, herein, not only a technique forcollecting information in the human body but also a technique fortransmitting collected information to the outside of the human body arevery important.

In a general data transmitting method, there is a communication cablemethod applied to an endoscope developed for observing the stomach andintestines. In the communication cable method, a cable made of aconducting wire or an optic fiber is inserted into the human bodythrough throat of a patient. The communication cable method has highreliability and high data quality, however, a patient may suffer fromsevere pain during an endoscope operation.

In order to solve the above-mentioned problem, Given Imaging LTD. inIsrael has developed a capsule type endoscope called M2A. When a patientswallows the capsule type endoscope like a tablet, image data in thehuman body photographed by a camera of the endoscope is transmitted to areceiving unit located outside the human body, and then displayed in amonitor.

However, because the M2A employs a radio wave method as a signaltransmitting method, power consumption is increased, an operational timeis reduced, and receiving sensitivity is deteriorated due tointerference of various electric waves from the outside of the humanbody. In addition, because the M2A requires a radio transmitter such asa converter circuit for converting an image signal into a high frequencyand an antenna for signal transmission, a volume is increased andproduction cost is high, and also the high frequency may be harmful tothe human body. Accordingly, the present applicant has developed a humanbody communication system capable of transmitting data about the insideof the human body to the outside of the human body with a low frequencycurrent by using the human body as a conductor.

In the human body communication system, an electric potential differencebetween transmitting electrodes that are formed on the surface of thecapsule type endoscope put in the human body generates a current. As thecurrent flows through the human body, it induces the voltage between tworeceiving electrodes installed on the surface of the human body, andaccordingly a receiving apparatus can receive data regarding the insideof the human body.

FIG. 1 shows a human body communication system including a capsule typeendoscope and two receiving electrodes. As depicted in FIG. 1, a capsuletype endoscope 10 is located inside the human body 1, and a receivingapparatus 20 is located outside the human body. A transmitting electrode11 is formed on the surface of both ends of the capsule type endoscope10, and the receiving apparatus 20 is connected with two receivingelectrodes 30 contacted to the surface of the human body. After medicalinformation collected by the capsule type endoscope 10 issignal-processed, when electric potential difference occurs between thetwo transmitting electrodes 11, a current flows through the human body 2since the two transmitting electrodes 11 are contacted with each otherthrough body fluids and form a closed-loop. The current flowing on thesurface of the human body induces a voltage between the two receivingelectrodes 30 installed on the surface of the human body. The inducedvoltage is in proportion to the current and distance between the tworeceiving electrodes 30. The receiving apparatus 20 located outside thehuman body senses a signal transmitted from the capsule type endoscope10 in the human body by the induced voltage.

However, when only the two receiving electrodes are used, if a directionof the current is vertical to an aligning direction of the receivingelectrodes, voltage is not induced or a small amount of voltage isinduced in the receiving electrodes. Accordingly, the receivingapparatus outside the human body may not receive accurately a signaltransmitted from the capsule type endoscope in the human body.

In more detail, as illustrated in FIG. 1, when the capsule typeendoscope 10 is located in an (A) direction, the aligning direction ofthe two receiving electrodes 30 is coincided with the direction of thetransmitting electrode 11. In this case, a maximum current flows betweenthe two receiving electrodes 30, so that the receiving apparatus 20obtains good receiving sensitivity. However, when the capsule typeendoscope 10 is located in a (B) direction, the aligning direction ofthe two receiving electrodes 30 is vertical to the direction of thetransmitting electrode 11. In this case, a current does not flow betweenthe two receiving electrodes 30, so that the receiving apparatus 20 cannot receive a signal transmitted from the capsule type endoscope 10.Briefly, because the receiving electrode 30 is fixed and aligningdirection of the transmitting electrode 11 is varied at any time,receiving sensitivity is varied as time elapses, a transmitted signalmay be lost, and accordingly quality of receiving information islowered.

In addition, when only the two receiving electrodes are used, positionof the capsule type endoscope in the human body can not be detected, andaccordingly the capsule type endoscope can not be used efficiently. Forexample, if we know a current position of the capsule type endoscopewhen the capsule type endoscope catches an abnormal symptom in thedigestive organs, an accurate operation and remedy can be performed.

TECHNICAL GIST OF THE PRESENT INVENTION

In order to solve the above-mentioned problems, it is an object of thepresent invention to provide a method and apparatus for receiving datain a human body communication system, which are capable of receivingdata with optimum sensitivity and extracting position information of acapsule type endoscope in the human body to use the position informationas medical information.

In order to achieve the above-mentioned object, a method for receivingdata in a human body communication system in accordance with the presentinvention comprise the steps of: selecting a pair of receivingelectrodes sequentially among plural receiving electrodes; processing avoltage value of the selected pair of receiving electrodes and storingit in a memory; performing a predetermined operations for values storedin the memory to select an optimum pair of receiving electrodes; andperforming image processing for a value corresponding to the optimumpair of receiving electrodes among the values stored in the memory.

In addition, an apparatus for receiving data in a human bodycommunication system in accordance with the present invention comprisesplural receiving electrodes installed on the surface of the human body;a switching means for selecting a pair of receiving electrodessequentially among the plural receiving electrodes; a processing meansfor processing a voltage value of a pair of receiving electrode selectedby the switching means; a memory for storing the processed value; acomparing-operating means for calculating a maximum value among valuesstored in the memory; an image processing means for performing imageprocessing for the maximum value; and a control means for controllingthe switching means and the comparing-operating means to provide themaximum value to the image processing means.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a diagram for showing problems occurred in data receiving inthe conventional human body communication system;

FIG. 2 is an exemplary view illustrating plural receiving electrodesinstalled on the surface of the human body in accordance with thepresent invention; and

FIG. 3 is a block diagram illustrating a receiving apparatus inaccordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the preferred embodiment of the present invention will bedescribed with reference to accompanying drawings.

FIG. 2 is a plane view illustrating plural receiving electrodesinstalled on the surface of the human body. As depicted in FIG. 2, eightreceiving electrodes are respectively installed on the surface of thehuman body, for example, the chest, the navel, an upper portion of theback, a lower portion of the back, the axillae and the sides. Whencurrent generated by electric potential difference between transmittingelectrodes 11 of a capsule type endoscope 10 reaches plural receivingelectrodes through the human body, a voltage is induced between the tworeceiving electrodes in proportion to the current and distance betweenthe two receiving electrodes.

With reference to FIG. 2, considering receiving electrodes 1 and 2 as apair of receiving electrodes, the greatest voltage is detected betweenreceiving electrodes 1 and 2. That is because an aligning direction ofthe transmitting electrode 11 is coincided with that of the receivingelectrodes 1 and 2 and also distance between the capsule type endoscope10 and the receiving electrodes is the shortest. On the other hand,considering receiving electrodes 3 and 4 or receiving electrodes 7 and 8as a pair of receiving electrodes, a voltage is not detected between thereceiving electrodes. That is because an aligning direction of thetransmitting electrode 11 of the capsule type endoscope 10 is verticalto an aligning direction of the receiving electrodes. In addition,considering receiving electrodes 5 and 6 as a pair of receivingelectrodes, voltage between the receiving electrodes 5 and 6 is lessthan that between the receiving electrodes 1 and 2. That is because analigning direction of the transmitting electrode 11 of the capsule typeendoscope 10 is coincided with an aligning direction of the receivingelectrodes, but distance between the capsule type endoscope 10 and thereceiving electrodes 5 and 6 is farther than that between the capsuletype endoscope 10 and the receiving electrodes 1 and 2.

As described-above, by measuring and comparing voltages between eachpair of receiving electrodes, we select the receiving electrodes 1 and 2to obtain better receiving sensitivity from the fact that the voltagebetween the receiving electrodes 1 and 2 is the greatest. In addition,we know the capsule type endoscope is located closer to the receivingelectrodes 1 and 2 from the fact that a voltage of the receivingelectrodes 1 and 2 is greater than that of the receiving electrodes 5and 6.

An accurate position of the capsule type endoscope 10 in the human bodycan be extracted by comparing and operating voltages sensed in each pairof receiving electrodes at predetermined time-intervals. Also, a movingpath, speed and direction, etc. of the capsule type endoscope in thehuman body can be known by processing an extracted position of thecapsule type endoscope 10 sequentially.

In the embodiment of the present invention, flat-arranged pluralreceiving electrodes are described, however, the present invention isnot limited by that. It is possible to extract three-dimensionalposition and direction of the capsule type endoscope 10 by distributingplural receiving electrodes onto the up/down, front/back and left/rightof the human body.

FIG. 3 is a block diagram illustrating a receiving apparatus havingplural receiving electrodes in accordance with the present invention. Asdepicted in FIG. 3, N receiving electrodes are respectively connected toa first switching circuit 21 and a second switching circuit 22 of areceiving apparatus 30. An output line of the first switching circuit 21is connected to a plus (+) terminal of a differential amplifier 23, andan output line of the second switching circuit 22 is connected to aminus (−) terminal of the differential amplifier 23. Under the controlof a control circuit 28, the switching circuits 22, 23 respectivelyselect only one among inputs from the N receiving electrodes.

The operation of the receiving apparatus 30 will be described in detail.First, when the first switching circuit 21 selects the receivingelectrode 1 and the second switching circuit 22 selects the receivingelectrode 2, a signal voltage between the receiving electrodes 1 and 2is transmitted to the differential amplifier 23 to be amplified. Theamplified signal passes a band pass filter 24 where noise is removed.The signal passing the band pass filter 24 is converted into a digitalsignal in an A/D converter 25 and is stored in a memory 27. Next, as thefirst switching circuit 21 maintains the receiving electrode 1, thesecond switching circuit 22 selects the receiving electrode 3. And thena signal voltage between the receiving electrodes 1 and 3 is stored in adifferent address of the memory 27 through the above-mentioned process.Continuously, as the first switching circuit 21 maintains the receivingelectrode 1, the second switching circuit 22 selects the receivingelectrode 4, 5, . . . and N, and then signal voltages between thereceiving electrode 1 and the other receiving electrodes aresequentially stored in the memory 27.

Likewise, as the first switching circuit 21 maintains selection of thereceiving electrode 2, the second switching circuit 22 selects the otherreceiving electrodes 1, 3, . . . and N sequentially, and then signalvoltages between the receiving electrode 2 and the other receivingelectrodes are sequentially stored in the memory 27. As described above,if the first switching circuit 21 selects the receiving electrode 3, 4,. . . and N sequentially and the second switching circuit 22 selects theother receiving electrodes sequentially, finally the (N-1)² number ofsignal voltages are stored in the memory 27. Of course, signal voltagesbetween the receiving electrodes may be sampled several times (more thantwo times) for an average value to be stored. Or, an average value of avoltage waveform for a certain time may be stored. In addition, in orderto reduce memory capacity and processing time, once-selected pair ofreceiving electrodes is no longer selected and the only _(n)C₂ number ofa pair of receiving electrodes may be selected.

A comparing-operating circuit 29 compares signal voltage values storedin the memory 27 and obtains the greatest value. From that result of thecomparing-operating circuit 29, it can be known a direction of thecapsule type endoscope 10 is similar to an aligning direction of thepair of receiving electrodes in which the greatest value occurs. Inaddition, the comparing-operating circuit 29 may extract athree-dimensional position of the capsule type endoscope 10 by comparingand operating signal voltage values stored in the memory 27 and store itagain in the memory 27.

The control circuit 28 selects the pair of receiving electrodes in whichthe greatest voltage occurs as communication electrodes, and accordinglya signal transmitted from the capsule type endoscope 10 in the humanbody can be received with the best receiving sensitivity. In moredetail, a signal of the pair of receiving electrodes in which thegreatest receiving voltage occurs is processed in an image processingcircuit 26.

The above-described a pair of receiving electrodes combining procedure,signal voltage processing procedure, comparing-operating procedure andoptimum pair of receiving electrodes selecting procedure, etc. areproceeded at a very quick speed (within 10 msec) and repeated at regulartime-intervals (per 5 seconds). Accordingly, information transmittedfrom the capsule type endoscope 10 can be always received through anoptimum pair of receiving electrodes. In addition, a moving path, aspeed and a direction of the capsule type endoscope 10 in the human bodycan be measured by storing calculated position information in the memory27 sequentially.

INDUSTRIAL APPLICABILITY

In the present invention, information transmitted from a capsule typeendoscope using the human body as a communication conductor can bereceived with optimum receiving sensitivity to a receiving apparatushaving plural receiving electrodes. Accordingly, it is possible toimprove quality of received information, grasp a moving path, a speedand a direction of the capsule type endoscope in the human body and usethem as medical information.

1. A method for receiving data in a human body communication system, comprising the steps of: selecting a pair of receiving electrodes from among plural receiving electrodes placed on the surface of the human body; processing a voltage value sensed by and induced at the selected pair of receiving electrodes and storing it in a memory, wherein the voltage is induced by a current flowing in the human body, the current being generated by an electric potential difference between spaced transmitting electrodes located inside the human body; repeating the selecting and processing steps for at least an additional pair of receiving electrodes; performing predetermined operations for values stored in the memory to select an optimum pair of receiving electrodes; and performing image processing for a value corresponding to the optimum pair of receiving electrodes among the values stored in the memory.
 2. The method of claim 1, wherein the step of processing the voltage comprises the sub-steps of: amplifying the voltage value; removing noise in the amplified signal; and converting the noise-removed analog signal into a digital signal.
 3. The method of claim 1, wherein the values stored in the memory are averages of voltage values sampled more than two times or averages of voltage waveforms for a given time.
 4. The method of claim 1, wherein a pair of receiving electrodes corresponding to a maximum value among the values stored in the memory is selected as the optimum pair of receiving electrodes.
 5. The method of claim 1, further comprising the step of: calculating position information of a sensor from the position of the optimum pair of receiving electrodes and storing it in the memory sequentially.
 6. The method of claim 5, wherein a moving path, a speed and a direction of the sensor are extracted from the position information.
 7. An apparatus for receiving data in a human body communication system using plural receiving electrodes installable on the surface of the human body, the apparatus comprising: a switching device for selecting a pair of receiving electrodes from among the plural receiving electrodes; a processor for processing a voltage value induced at the pair of receiving electrodes selected by the switching device, wherein the voltage is induced by a current flowing in the human body, and the current is generated by an electric potential difference between two transmitting electrodes located inside the human body; a memory for storing voltage values; a comparator for determining a maximum value among the values stored in the memory; an image processor for performing image processing of data corresponding to an optimum pair of receiving electrodes associated with the maximum value; and a control for controlling the switching device and the comparator.
 8. The apparatus of claim 7, wherein the switching device includes a first switching circuit and a second switching circuit to which the plural receiving electrodes are connected respectively.
 9. The apparatus of claim 7, wherein the processor includes: a differential amplifier for amplifying a voltage output from the switching device; a band pass filter for removing noise in the amplified signal; and an A/D converter for converting the noise-removed analog signal into a digital signal.
 10. The apparatus of claim 7, wherein the values stored in the memory are averages of voltage values sampled more than two times or are averages of voltage waveforms for a given time.
 11. The apparatus of claim 7, wherein the comparator is operable to calculate position information of a sensor from the position of a pair of receiving electrodes corresponding to the maximum value and store the position information in the memory sequentially.
 12. The apparatus of claim 11, including a further processor operable to extract a moving path, a speed and a direction of the sensor from the position information. 